It was narrated that Ibn Sirin said:

"Some of those who prayed the Subh prayer with the Messenger of Allah ﷺ narrated to me that when he said: Sami'Allahu liman hamidah (Allah hears those who praise Him)' in the second rak'ah, he stood for a while."

أَخْبَرَنَا إِسْمَاعِيلُ بْنُ مَسْعُودٍ، قَالَ حَدَّثَنَا بِشْرُ بْنُ الْمُفَضَّلِ، عَنْ يُونُسَ، عَنِ ابْنِ سِيرِينَ، قَالَ حَدَّثَنِي بَعْضُ، مَنْ صَلَّى مَعَ رَسُولِ اللَّهِ ﷺ صَلاَةَ الصُّبْحِ فَلَمَّا قَالَ " سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ " . فِي الرَّكْعَةِ الثَّانِيَةِ قَامَ هُنَيْهَةً .